Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * linux/kernel/seccomp.c
4 : *
5 : * Copyright 2004-2005 Andrea Arcangeli <andrea@cpushare.com>
6 : *
7 : * Copyright (C) 2012 Google, Inc.
8 : * Will Drewry <wad@chromium.org>
9 : *
10 : * This defines a simple but solid secure-computing facility.
11 : *
12 : * Mode 1 uses a fixed list of allowed system calls.
13 : * Mode 2 allows user-defined system call filters in the form
14 : * of Berkeley Packet Filters/Linux Socket Filters.
15 : */
16 : #define pr_fmt(fmt) "seccomp: " fmt
17 :
18 : #include <linux/refcount.h>
19 : #include <linux/audit.h>
20 : #include <linux/compat.h>
21 : #include <linux/coredump.h>
22 : #include <linux/kmemleak.h>
23 : #include <linux/nospec.h>
24 : #include <linux/prctl.h>
25 : #include <linux/sched.h>
26 : #include <linux/sched/task_stack.h>
27 : #include <linux/seccomp.h>
28 : #include <linux/slab.h>
29 : #include <linux/syscalls.h>
30 : #include <linux/sysctl.h>
31 :
32 : /* Not exposed in headers: strictly internal use only. */
33 : #define SECCOMP_MODE_DEAD (SECCOMP_MODE_FILTER + 1)
34 :
35 : #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
36 : #include <asm/syscall.h>
37 : #endif
38 :
39 : #ifdef CONFIG_SECCOMP_FILTER
40 : #include <linux/file.h>
41 : #include <linux/filter.h>
42 : #include <linux/pid.h>
43 : #include <linux/ptrace.h>
44 : #include <linux/capability.h>
45 : #include <linux/uaccess.h>
46 : #include <linux/anon_inodes.h>
47 : #include <linux/lockdep.h>
48 :
49 : /*
50 : * When SECCOMP_IOCTL_NOTIF_ID_VALID was first introduced, it had the
51 : * wrong direction flag in the ioctl number. This is the broken one,
52 : * which the kernel needs to keep supporting until all userspaces stop
53 : * using the wrong command number.
54 : */
55 : #define SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR SECCOMP_IOR(2, __u64)
56 :
57 : enum notify_state {
58 : SECCOMP_NOTIFY_INIT,
59 : SECCOMP_NOTIFY_SENT,
60 : SECCOMP_NOTIFY_REPLIED,
61 : };
62 :
63 : struct seccomp_knotif {
64 : /* The struct pid of the task whose filter triggered the notification */
65 : struct task_struct *task;
66 :
67 : /* The "cookie" for this request; this is unique for this filter. */
68 : u64 id;
69 :
70 : /*
71 : * The seccomp data. This pointer is valid the entire time this
72 : * notification is active, since it comes from __seccomp_filter which
73 : * eclipses the entire lifecycle here.
74 : */
75 : const struct seccomp_data *data;
76 :
77 : /*
78 : * Notification states. When SECCOMP_RET_USER_NOTIF is returned, a
79 : * struct seccomp_knotif is created and starts out in INIT. Once the
80 : * handler reads the notification off of an FD, it transitions to SENT.
81 : * If a signal is received the state transitions back to INIT and
82 : * another message is sent. When the userspace handler replies, state
83 : * transitions to REPLIED.
84 : */
85 : enum notify_state state;
86 :
87 : /* The return values, only valid when in SECCOMP_NOTIFY_REPLIED */
88 : int error;
89 : long val;
90 : u32 flags;
91 :
92 : /*
93 : * Signals when this has changed states, such as the listener
94 : * dying, a new seccomp addfd message, or changing to REPLIED
95 : */
96 : struct completion ready;
97 :
98 : struct list_head list;
99 :
100 : /* outstanding addfd requests */
101 : struct list_head addfd;
102 : };
103 :
104 : /**
105 : * struct seccomp_kaddfd - container for seccomp_addfd ioctl messages
106 : *
107 : * @file: A reference to the file to install in the other task
108 : * @fd: The fd number to install it at. If the fd number is -1, it means the
109 : * installing process should allocate the fd as normal.
110 : * @flags: The flags for the new file descriptor. At the moment, only O_CLOEXEC
111 : * is allowed.
112 : * @ioctl_flags: The flags used for the seccomp_addfd ioctl.
113 : * @ret: The return value of the installing process. It is set to the fd num
114 : * upon success (>= 0).
115 : * @completion: Indicates that the installing process has completed fd
116 : * installation, or gone away (either due to successful
117 : * reply, or signal)
118 : *
119 : */
120 : struct seccomp_kaddfd {
121 : struct file *file;
122 : int fd;
123 : unsigned int flags;
124 : __u32 ioctl_flags;
125 :
126 : union {
127 : bool setfd;
128 : /* To only be set on reply */
129 : int ret;
130 : };
131 : struct completion completion;
132 : struct list_head list;
133 : };
134 :
135 : /**
136 : * struct notification - container for seccomp userspace notifications. Since
137 : * most seccomp filters will not have notification listeners attached and this
138 : * structure is fairly large, we store the notification-specific stuff in a
139 : * separate structure.
140 : *
141 : * @request: A semaphore that users of this notification can wait on for
142 : * changes. Actual reads and writes are still controlled with
143 : * filter->notify_lock.
144 : * @next_id: The id of the next request.
145 : * @notifications: A list of struct seccomp_knotif elements.
146 : */
147 : struct notification {
148 : struct semaphore request;
149 : u64 next_id;
150 : struct list_head notifications;
151 : };
152 :
153 : #ifdef SECCOMP_ARCH_NATIVE
154 : /**
155 : * struct action_cache - per-filter cache of seccomp actions per
156 : * arch/syscall pair
157 : *
158 : * @allow_native: A bitmap where each bit represents whether the
159 : * filter will always allow the syscall, for the
160 : * native architecture.
161 : * @allow_compat: A bitmap where each bit represents whether the
162 : * filter will always allow the syscall, for the
163 : * compat architecture.
164 : */
165 : struct action_cache {
166 : DECLARE_BITMAP(allow_native, SECCOMP_ARCH_NATIVE_NR);
167 : #ifdef SECCOMP_ARCH_COMPAT
168 : DECLARE_BITMAP(allow_compat, SECCOMP_ARCH_COMPAT_NR);
169 : #endif
170 : };
171 : #else
172 : struct action_cache { };
173 :
174 : static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
175 : const struct seccomp_data *sd)
176 : {
177 : return false;
178 : }
179 :
180 : static inline void seccomp_cache_prepare(struct seccomp_filter *sfilter)
181 : {
182 : }
183 : #endif /* SECCOMP_ARCH_NATIVE */
184 :
185 : /**
186 : * struct seccomp_filter - container for seccomp BPF programs
187 : *
188 : * @refs: Reference count to manage the object lifetime.
189 : * A filter's reference count is incremented for each directly
190 : * attached task, once for the dependent filter, and if
191 : * requested for the user notifier. When @refs reaches zero,
192 : * the filter can be freed.
193 : * @users: A filter's @users count is incremented for each directly
194 : * attached task (filter installation, fork(), thread_sync),
195 : * and once for the dependent filter (tracked in filter->prev).
196 : * When it reaches zero it indicates that no direct or indirect
197 : * users of that filter exist. No new tasks can get associated with
198 : * this filter after reaching 0. The @users count is always smaller
199 : * or equal to @refs. Hence, reaching 0 for @users does not mean
200 : * the filter can be freed.
201 : * @cache: cache of arch/syscall mappings to actions
202 : * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
203 : * @wait_killable_recv: Put notifying process in killable state once the
204 : * notification is received by the userspace listener.
205 : * @prev: points to a previously installed, or inherited, filter
206 : * @prog: the BPF program to evaluate
207 : * @notif: the struct that holds all notification related information
208 : * @notify_lock: A lock for all notification-related accesses.
209 : * @wqh: A wait queue for poll if a notifier is in use.
210 : *
211 : * seccomp_filter objects are organized in a tree linked via the @prev
212 : * pointer. For any task, it appears to be a singly-linked list starting
213 : * with current->seccomp.filter, the most recently attached or inherited filter.
214 : * However, multiple filters may share a @prev node, by way of fork(), which
215 : * results in a unidirectional tree existing in memory. This is similar to
216 : * how namespaces work.
217 : *
218 : * seccomp_filter objects should never be modified after being attached
219 : * to a task_struct (other than @refs).
220 : */
221 : struct seccomp_filter {
222 : refcount_t refs;
223 : refcount_t users;
224 : bool log;
225 : bool wait_killable_recv;
226 : struct action_cache cache;
227 : struct seccomp_filter *prev;
228 : struct bpf_prog *prog;
229 : struct notification *notif;
230 : struct mutex notify_lock;
231 : wait_queue_head_t wqh;
232 : };
233 :
234 : /* Limit any path through the tree to 256KB worth of instructions. */
235 : #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
236 :
237 : /*
238 : * Endianness is explicitly ignored and left for BPF program authors to manage
239 : * as per the specific architecture.
240 : */
241 : static void populate_seccomp_data(struct seccomp_data *sd)
242 : {
243 : /*
244 : * Instead of using current_pt_reg(), we're already doing the work
245 : * to safely fetch "current", so just use "task" everywhere below.
246 : */
247 : struct task_struct *task = current;
248 : struct pt_regs *regs = task_pt_regs(task);
249 : unsigned long args[6];
250 :
251 : sd->nr = syscall_get_nr(task, regs);
252 : sd->arch = syscall_get_arch(task);
253 : syscall_get_arguments(task, regs, args);
254 : sd->args[0] = args[0];
255 : sd->args[1] = args[1];
256 : sd->args[2] = args[2];
257 : sd->args[3] = args[3];
258 : sd->args[4] = args[4];
259 : sd->args[5] = args[5];
260 : sd->instruction_pointer = KSTK_EIP(task);
261 : }
262 :
263 : /**
264 : * seccomp_check_filter - verify seccomp filter code
265 : * @filter: filter to verify
266 : * @flen: length of filter
267 : *
268 : * Takes a previously checked filter (by bpf_check_classic) and
269 : * redirects all filter code that loads struct sk_buff data
270 : * and related data through seccomp_bpf_load. It also
271 : * enforces length and alignment checking of those loads.
272 : *
273 : * Returns 0 if the rule set is legal or -EINVAL if not.
274 : */
275 : static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
276 : {
277 : int pc;
278 : for (pc = 0; pc < flen; pc++) {
279 : struct sock_filter *ftest = &filter[pc];
280 : u16 code = ftest->code;
281 : u32 k = ftest->k;
282 :
283 : switch (code) {
284 : case BPF_LD | BPF_W | BPF_ABS:
285 : ftest->code = BPF_LDX | BPF_W | BPF_ABS;
286 : /* 32-bit aligned and not out of bounds. */
287 : if (k >= sizeof(struct seccomp_data) || k & 3)
288 : return -EINVAL;
289 : continue;
290 : case BPF_LD | BPF_W | BPF_LEN:
291 : ftest->code = BPF_LD | BPF_IMM;
292 : ftest->k = sizeof(struct seccomp_data);
293 : continue;
294 : case BPF_LDX | BPF_W | BPF_LEN:
295 : ftest->code = BPF_LDX | BPF_IMM;
296 : ftest->k = sizeof(struct seccomp_data);
297 : continue;
298 : /* Explicitly include allowed calls. */
299 : case BPF_RET | BPF_K:
300 : case BPF_RET | BPF_A:
301 : case BPF_ALU | BPF_ADD | BPF_K:
302 : case BPF_ALU | BPF_ADD | BPF_X:
303 : case BPF_ALU | BPF_SUB | BPF_K:
304 : case BPF_ALU | BPF_SUB | BPF_X:
305 : case BPF_ALU | BPF_MUL | BPF_K:
306 : case BPF_ALU | BPF_MUL | BPF_X:
307 : case BPF_ALU | BPF_DIV | BPF_K:
308 : case BPF_ALU | BPF_DIV | BPF_X:
309 : case BPF_ALU | BPF_AND | BPF_K:
310 : case BPF_ALU | BPF_AND | BPF_X:
311 : case BPF_ALU | BPF_OR | BPF_K:
312 : case BPF_ALU | BPF_OR | BPF_X:
313 : case BPF_ALU | BPF_XOR | BPF_K:
314 : case BPF_ALU | BPF_XOR | BPF_X:
315 : case BPF_ALU | BPF_LSH | BPF_K:
316 : case BPF_ALU | BPF_LSH | BPF_X:
317 : case BPF_ALU | BPF_RSH | BPF_K:
318 : case BPF_ALU | BPF_RSH | BPF_X:
319 : case BPF_ALU | BPF_NEG:
320 : case BPF_LD | BPF_IMM:
321 : case BPF_LDX | BPF_IMM:
322 : case BPF_MISC | BPF_TAX:
323 : case BPF_MISC | BPF_TXA:
324 : case BPF_LD | BPF_MEM:
325 : case BPF_LDX | BPF_MEM:
326 : case BPF_ST:
327 : case BPF_STX:
328 : case BPF_JMP | BPF_JA:
329 : case BPF_JMP | BPF_JEQ | BPF_K:
330 : case BPF_JMP | BPF_JEQ | BPF_X:
331 : case BPF_JMP | BPF_JGE | BPF_K:
332 : case BPF_JMP | BPF_JGE | BPF_X:
333 : case BPF_JMP | BPF_JGT | BPF_K:
334 : case BPF_JMP | BPF_JGT | BPF_X:
335 : case BPF_JMP | BPF_JSET | BPF_K:
336 : case BPF_JMP | BPF_JSET | BPF_X:
337 : continue;
338 : default:
339 : return -EINVAL;
340 : }
341 : }
342 : return 0;
343 : }
344 :
345 : #ifdef SECCOMP_ARCH_NATIVE
346 : static inline bool seccomp_cache_check_allow_bitmap(const void *bitmap,
347 : size_t bitmap_size,
348 : int syscall_nr)
349 : {
350 : if (unlikely(syscall_nr < 0 || syscall_nr >= bitmap_size))
351 : return false;
352 : syscall_nr = array_index_nospec(syscall_nr, bitmap_size);
353 :
354 : return test_bit(syscall_nr, bitmap);
355 : }
356 :
357 : /**
358 : * seccomp_cache_check_allow - lookup seccomp cache
359 : * @sfilter: The seccomp filter
360 : * @sd: The seccomp data to lookup the cache with
361 : *
362 : * Returns true if the seccomp_data is cached and allowed.
363 : */
364 : static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
365 : const struct seccomp_data *sd)
366 : {
367 : int syscall_nr = sd->nr;
368 : const struct action_cache *cache = &sfilter->cache;
369 :
370 : #ifndef SECCOMP_ARCH_COMPAT
371 : /* A native-only architecture doesn't need to check sd->arch. */
372 : return seccomp_cache_check_allow_bitmap(cache->allow_native,
373 : SECCOMP_ARCH_NATIVE_NR,
374 : syscall_nr);
375 : #else
376 : if (likely(sd->arch == SECCOMP_ARCH_NATIVE))
377 : return seccomp_cache_check_allow_bitmap(cache->allow_native,
378 : SECCOMP_ARCH_NATIVE_NR,
379 : syscall_nr);
380 : if (likely(sd->arch == SECCOMP_ARCH_COMPAT))
381 : return seccomp_cache_check_allow_bitmap(cache->allow_compat,
382 : SECCOMP_ARCH_COMPAT_NR,
383 : syscall_nr);
384 : #endif /* SECCOMP_ARCH_COMPAT */
385 :
386 : WARN_ON_ONCE(true);
387 : return false;
388 : }
389 : #endif /* SECCOMP_ARCH_NATIVE */
390 :
391 : #define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL)))
392 : /**
393 : * seccomp_run_filters - evaluates all seccomp filters against @sd
394 : * @sd: optional seccomp data to be passed to filters
395 : * @match: stores struct seccomp_filter that resulted in the return value,
396 : * unless filter returned SECCOMP_RET_ALLOW, in which case it will
397 : * be unchanged.
398 : *
399 : * Returns valid seccomp BPF response codes.
400 : */
401 : static u32 seccomp_run_filters(const struct seccomp_data *sd,
402 : struct seccomp_filter **match)
403 : {
404 : u32 ret = SECCOMP_RET_ALLOW;
405 : /* Make sure cross-thread synced filter points somewhere sane. */
406 : struct seccomp_filter *f =
407 : READ_ONCE(current->seccomp.filter);
408 :
409 : /* Ensure unexpected behavior doesn't result in failing open. */
410 : if (WARN_ON(f == NULL))
411 : return SECCOMP_RET_KILL_PROCESS;
412 :
413 : if (seccomp_cache_check_allow(f, sd))
414 : return SECCOMP_RET_ALLOW;
415 :
416 : /*
417 : * All filters in the list are evaluated and the lowest BPF return
418 : * value always takes priority (ignoring the DATA).
419 : */
420 : for (; f; f = f->prev) {
421 : u32 cur_ret = bpf_prog_run_pin_on_cpu(f->prog, sd);
422 :
423 : if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) {
424 : ret = cur_ret;
425 : *match = f;
426 : }
427 : }
428 : return ret;
429 : }
430 : #endif /* CONFIG_SECCOMP_FILTER */
431 :
432 : static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
433 : {
434 0 : assert_spin_locked(¤t->sighand->siglock);
435 :
436 0 : if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
437 : return false;
438 :
439 : return true;
440 : }
441 :
442 0 : void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { }
443 :
444 : static inline void seccomp_assign_mode(struct task_struct *task,
445 : unsigned long seccomp_mode,
446 : unsigned long flags)
447 : {
448 : assert_spin_locked(&task->sighand->siglock);
449 :
450 0 : task->seccomp.mode = seccomp_mode;
451 : /*
452 : * Make sure SYSCALL_WORK_SECCOMP cannot be set before the mode (and
453 : * filter) is set.
454 : */
455 0 : smp_mb__before_atomic();
456 : /* Assume default seccomp processes want spec flaw mitigation. */
457 : if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
458 0 : arch_seccomp_spec_mitigate(task);
459 0 : set_task_syscall_work(task, SECCOMP);
460 : }
461 :
462 : #ifdef CONFIG_SECCOMP_FILTER
463 : /* Returns 1 if the parent is an ancestor of the child. */
464 : static int is_ancestor(struct seccomp_filter *parent,
465 : struct seccomp_filter *child)
466 : {
467 : /* NULL is the root ancestor. */
468 : if (parent == NULL)
469 : return 1;
470 : for (; child; child = child->prev)
471 : if (child == parent)
472 : return 1;
473 : return 0;
474 : }
475 :
476 : /**
477 : * seccomp_can_sync_threads: checks if all threads can be synchronized
478 : *
479 : * Expects sighand and cred_guard_mutex locks to be held.
480 : *
481 : * Returns 0 on success, -ve on error, or the pid of a thread which was
482 : * either not in the correct seccomp mode or did not have an ancestral
483 : * seccomp filter.
484 : */
485 : static inline pid_t seccomp_can_sync_threads(void)
486 : {
487 : struct task_struct *thread, *caller;
488 :
489 : BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex));
490 : assert_spin_locked(¤t->sighand->siglock);
491 :
492 : /* Validate all threads being eligible for synchronization. */
493 : caller = current;
494 : for_each_thread(caller, thread) {
495 : pid_t failed;
496 :
497 : /* Skip current, since it is initiating the sync. */
498 : if (thread == caller)
499 : continue;
500 :
501 : if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
502 : (thread->seccomp.mode == SECCOMP_MODE_FILTER &&
503 : is_ancestor(thread->seccomp.filter,
504 : caller->seccomp.filter)))
505 : continue;
506 :
507 : /* Return the first thread that cannot be synchronized. */
508 : failed = task_pid_vnr(thread);
509 : /* If the pid cannot be resolved, then return -ESRCH */
510 : if (WARN_ON(failed == 0))
511 : failed = -ESRCH;
512 : return failed;
513 : }
514 :
515 : return 0;
516 : }
517 :
518 : static inline void seccomp_filter_free(struct seccomp_filter *filter)
519 : {
520 : if (filter) {
521 : bpf_prog_destroy(filter->prog);
522 : kfree(filter);
523 : }
524 : }
525 :
526 : static void __seccomp_filter_orphan(struct seccomp_filter *orig)
527 : {
528 : while (orig && refcount_dec_and_test(&orig->users)) {
529 : if (waitqueue_active(&orig->wqh))
530 : wake_up_poll(&orig->wqh, EPOLLHUP);
531 : orig = orig->prev;
532 : }
533 : }
534 :
535 : static void __put_seccomp_filter(struct seccomp_filter *orig)
536 : {
537 : /* Clean up single-reference branches iteratively. */
538 : while (orig && refcount_dec_and_test(&orig->refs)) {
539 : struct seccomp_filter *freeme = orig;
540 : orig = orig->prev;
541 : seccomp_filter_free(freeme);
542 : }
543 : }
544 :
545 : static void __seccomp_filter_release(struct seccomp_filter *orig)
546 : {
547 : /* Notify about any unused filters in the task's former filter tree. */
548 : __seccomp_filter_orphan(orig);
549 : /* Finally drop all references to the task's former tree. */
550 : __put_seccomp_filter(orig);
551 : }
552 :
553 : /**
554 : * seccomp_filter_release - Detach the task from its filter tree,
555 : * drop its reference count, and notify
556 : * about unused filters
557 : *
558 : * This function should only be called when the task is exiting as
559 : * it detaches it from its filter tree. As such, READ_ONCE() and
560 : * barriers are not needed here, as would normally be needed.
561 : */
562 : void seccomp_filter_release(struct task_struct *tsk)
563 : {
564 : struct seccomp_filter *orig = tsk->seccomp.filter;
565 :
566 : /* We are effectively holding the siglock by not having any sighand. */
567 : WARN_ON(tsk->sighand != NULL);
568 :
569 : /* Detach task from its filter tree. */
570 : tsk->seccomp.filter = NULL;
571 : __seccomp_filter_release(orig);
572 : }
573 :
574 : /**
575 : * seccomp_sync_threads: sets all threads to use current's filter
576 : *
577 : * Expects sighand and cred_guard_mutex locks to be held, and for
578 : * seccomp_can_sync_threads() to have returned success already
579 : * without dropping the locks.
580 : *
581 : */
582 : static inline void seccomp_sync_threads(unsigned long flags)
583 : {
584 : struct task_struct *thread, *caller;
585 :
586 : BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex));
587 : assert_spin_locked(¤t->sighand->siglock);
588 :
589 : /* Synchronize all threads. */
590 : caller = current;
591 : for_each_thread(caller, thread) {
592 : /* Skip current, since it needs no changes. */
593 : if (thread == caller)
594 : continue;
595 :
596 : /* Get a task reference for the new leaf node. */
597 : get_seccomp_filter(caller);
598 :
599 : /*
600 : * Drop the task reference to the shared ancestor since
601 : * current's path will hold a reference. (This also
602 : * allows a put before the assignment.)
603 : */
604 : __seccomp_filter_release(thread->seccomp.filter);
605 :
606 : /* Make our new filter tree visible. */
607 : smp_store_release(&thread->seccomp.filter,
608 : caller->seccomp.filter);
609 : atomic_set(&thread->seccomp.filter_count,
610 : atomic_read(&caller->seccomp.filter_count));
611 :
612 : /*
613 : * Don't let an unprivileged task work around
614 : * the no_new_privs restriction by creating
615 : * a thread that sets it up, enters seccomp,
616 : * then dies.
617 : */
618 : if (task_no_new_privs(caller))
619 : task_set_no_new_privs(thread);
620 :
621 : /*
622 : * Opt the other thread into seccomp if needed.
623 : * As threads are considered to be trust-realm
624 : * equivalent (see ptrace_may_access), it is safe to
625 : * allow one thread to transition the other.
626 : */
627 : if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
628 : seccomp_assign_mode(thread, SECCOMP_MODE_FILTER,
629 : flags);
630 : }
631 : }
632 :
633 : /**
634 : * seccomp_prepare_filter: Prepares a seccomp filter for use.
635 : * @fprog: BPF program to install
636 : *
637 : * Returns filter on success or an ERR_PTR on failure.
638 : */
639 : static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
640 : {
641 : struct seccomp_filter *sfilter;
642 : int ret;
643 : const bool save_orig =
644 : #if defined(CONFIG_CHECKPOINT_RESTORE) || defined(SECCOMP_ARCH_NATIVE)
645 : true;
646 : #else
647 : false;
648 : #endif
649 :
650 : if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
651 : return ERR_PTR(-EINVAL);
652 :
653 : BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
654 :
655 : /*
656 : * Installing a seccomp filter requires that the task has
657 : * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
658 : * This avoids scenarios where unprivileged tasks can affect the
659 : * behavior of privileged children.
660 : */
661 : if (!task_no_new_privs(current) &&
662 : !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
663 : return ERR_PTR(-EACCES);
664 :
665 : /* Allocate a new seccomp_filter */
666 : sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN);
667 : if (!sfilter)
668 : return ERR_PTR(-ENOMEM);
669 :
670 : mutex_init(&sfilter->notify_lock);
671 : ret = bpf_prog_create_from_user(&sfilter->prog, fprog,
672 : seccomp_check_filter, save_orig);
673 : if (ret < 0) {
674 : kfree(sfilter);
675 : return ERR_PTR(ret);
676 : }
677 :
678 : refcount_set(&sfilter->refs, 1);
679 : refcount_set(&sfilter->users, 1);
680 : init_waitqueue_head(&sfilter->wqh);
681 :
682 : return sfilter;
683 : }
684 :
685 : /**
686 : * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
687 : * @user_filter: pointer to the user data containing a sock_fprog.
688 : *
689 : * Returns 0 on success and non-zero otherwise.
690 : */
691 : static struct seccomp_filter *
692 : seccomp_prepare_user_filter(const char __user *user_filter)
693 : {
694 : struct sock_fprog fprog;
695 : struct seccomp_filter *filter = ERR_PTR(-EFAULT);
696 :
697 : #ifdef CONFIG_COMPAT
698 : if (in_compat_syscall()) {
699 : struct compat_sock_fprog fprog32;
700 : if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
701 : goto out;
702 : fprog.len = fprog32.len;
703 : fprog.filter = compat_ptr(fprog32.filter);
704 : } else /* falls through to the if below. */
705 : #endif
706 : if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
707 : goto out;
708 : filter = seccomp_prepare_filter(&fprog);
709 : out:
710 : return filter;
711 : }
712 :
713 : #ifdef SECCOMP_ARCH_NATIVE
714 : /**
715 : * seccomp_is_const_allow - check if filter is constant allow with given data
716 : * @fprog: The BPF programs
717 : * @sd: The seccomp data to check against, only syscall number and arch
718 : * number are considered constant.
719 : */
720 : static bool seccomp_is_const_allow(struct sock_fprog_kern *fprog,
721 : struct seccomp_data *sd)
722 : {
723 : unsigned int reg_value = 0;
724 : unsigned int pc;
725 : bool op_res;
726 :
727 : if (WARN_ON_ONCE(!fprog))
728 : return false;
729 :
730 : for (pc = 0; pc < fprog->len; pc++) {
731 : struct sock_filter *insn = &fprog->filter[pc];
732 : u16 code = insn->code;
733 : u32 k = insn->k;
734 :
735 : switch (code) {
736 : case BPF_LD | BPF_W | BPF_ABS:
737 : switch (k) {
738 : case offsetof(struct seccomp_data, nr):
739 : reg_value = sd->nr;
740 : break;
741 : case offsetof(struct seccomp_data, arch):
742 : reg_value = sd->arch;
743 : break;
744 : default:
745 : /* can't optimize (non-constant value load) */
746 : return false;
747 : }
748 : break;
749 : case BPF_RET | BPF_K:
750 : /* reached return with constant values only, check allow */
751 : return k == SECCOMP_RET_ALLOW;
752 : case BPF_JMP | BPF_JA:
753 : pc += insn->k;
754 : break;
755 : case BPF_JMP | BPF_JEQ | BPF_K:
756 : case BPF_JMP | BPF_JGE | BPF_K:
757 : case BPF_JMP | BPF_JGT | BPF_K:
758 : case BPF_JMP | BPF_JSET | BPF_K:
759 : switch (BPF_OP(code)) {
760 : case BPF_JEQ:
761 : op_res = reg_value == k;
762 : break;
763 : case BPF_JGE:
764 : op_res = reg_value >= k;
765 : break;
766 : case BPF_JGT:
767 : op_res = reg_value > k;
768 : break;
769 : case BPF_JSET:
770 : op_res = !!(reg_value & k);
771 : break;
772 : default:
773 : /* can't optimize (unknown jump) */
774 : return false;
775 : }
776 :
777 : pc += op_res ? insn->jt : insn->jf;
778 : break;
779 : case BPF_ALU | BPF_AND | BPF_K:
780 : reg_value &= k;
781 : break;
782 : default:
783 : /* can't optimize (unknown insn) */
784 : return false;
785 : }
786 : }
787 :
788 : /* ran off the end of the filter?! */
789 : WARN_ON(1);
790 : return false;
791 : }
792 :
793 : static void seccomp_cache_prepare_bitmap(struct seccomp_filter *sfilter,
794 : void *bitmap, const void *bitmap_prev,
795 : size_t bitmap_size, int arch)
796 : {
797 : struct sock_fprog_kern *fprog = sfilter->prog->orig_prog;
798 : struct seccomp_data sd;
799 : int nr;
800 :
801 : if (bitmap_prev) {
802 : /* The new filter must be as restrictive as the last. */
803 : bitmap_copy(bitmap, bitmap_prev, bitmap_size);
804 : } else {
805 : /* Before any filters, all syscalls are always allowed. */
806 : bitmap_fill(bitmap, bitmap_size);
807 : }
808 :
809 : for (nr = 0; nr < bitmap_size; nr++) {
810 : /* No bitmap change: not a cacheable action. */
811 : if (!test_bit(nr, bitmap))
812 : continue;
813 :
814 : sd.nr = nr;
815 : sd.arch = arch;
816 :
817 : /* No bitmap change: continue to always allow. */
818 : if (seccomp_is_const_allow(fprog, &sd))
819 : continue;
820 :
821 : /*
822 : * Not a cacheable action: always run filters.
823 : * atomic clear_bit() not needed, filter not visible yet.
824 : */
825 : __clear_bit(nr, bitmap);
826 : }
827 : }
828 :
829 : /**
830 : * seccomp_cache_prepare - emulate the filter to find cacheable syscalls
831 : * @sfilter: The seccomp filter
832 : *
833 : * Returns 0 if successful or -errno if error occurred.
834 : */
835 : static void seccomp_cache_prepare(struct seccomp_filter *sfilter)
836 : {
837 : struct action_cache *cache = &sfilter->cache;
838 : const struct action_cache *cache_prev =
839 : sfilter->prev ? &sfilter->prev->cache : NULL;
840 :
841 : seccomp_cache_prepare_bitmap(sfilter, cache->allow_native,
842 : cache_prev ? cache_prev->allow_native : NULL,
843 : SECCOMP_ARCH_NATIVE_NR,
844 : SECCOMP_ARCH_NATIVE);
845 :
846 : #ifdef SECCOMP_ARCH_COMPAT
847 : seccomp_cache_prepare_bitmap(sfilter, cache->allow_compat,
848 : cache_prev ? cache_prev->allow_compat : NULL,
849 : SECCOMP_ARCH_COMPAT_NR,
850 : SECCOMP_ARCH_COMPAT);
851 : #endif /* SECCOMP_ARCH_COMPAT */
852 : }
853 : #endif /* SECCOMP_ARCH_NATIVE */
854 :
855 : /**
856 : * seccomp_attach_filter: validate and attach filter
857 : * @flags: flags to change filter behavior
858 : * @filter: seccomp filter to add to the current process
859 : *
860 : * Caller must be holding current->sighand->siglock lock.
861 : *
862 : * Returns 0 on success, -ve on error, or
863 : * - in TSYNC mode: the pid of a thread which was either not in the correct
864 : * seccomp mode or did not have an ancestral seccomp filter
865 : * - in NEW_LISTENER mode: the fd of the new listener
866 : */
867 : static long seccomp_attach_filter(unsigned int flags,
868 : struct seccomp_filter *filter)
869 : {
870 : unsigned long total_insns;
871 : struct seccomp_filter *walker;
872 :
873 : assert_spin_locked(¤t->sighand->siglock);
874 :
875 : /* Validate resulting filter length. */
876 : total_insns = filter->prog->len;
877 : for (walker = current->seccomp.filter; walker; walker = walker->prev)
878 : total_insns += walker->prog->len + 4; /* 4 instr penalty */
879 : if (total_insns > MAX_INSNS_PER_PATH)
880 : return -ENOMEM;
881 :
882 : /* If thread sync has been requested, check that it is possible. */
883 : if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
884 : int ret;
885 :
886 : ret = seccomp_can_sync_threads();
887 : if (ret) {
888 : if (flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH)
889 : return -ESRCH;
890 : else
891 : return ret;
892 : }
893 : }
894 :
895 : /* Set log flag, if present. */
896 : if (flags & SECCOMP_FILTER_FLAG_LOG)
897 : filter->log = true;
898 :
899 : /* Set wait killable flag, if present. */
900 : if (flags & SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV)
901 : filter->wait_killable_recv = true;
902 :
903 : /*
904 : * If there is an existing filter, make it the prev and don't drop its
905 : * task reference.
906 : */
907 : filter->prev = current->seccomp.filter;
908 : seccomp_cache_prepare(filter);
909 : current->seccomp.filter = filter;
910 : atomic_inc(¤t->seccomp.filter_count);
911 :
912 : /* Now that the new filter is in place, synchronize to all threads. */
913 : if (flags & SECCOMP_FILTER_FLAG_TSYNC)
914 : seccomp_sync_threads(flags);
915 :
916 : return 0;
917 : }
918 :
919 : static void __get_seccomp_filter(struct seccomp_filter *filter)
920 : {
921 : refcount_inc(&filter->refs);
922 : }
923 :
924 : /* get_seccomp_filter - increments the reference count of the filter on @tsk */
925 : void get_seccomp_filter(struct task_struct *tsk)
926 : {
927 : struct seccomp_filter *orig = tsk->seccomp.filter;
928 : if (!orig)
929 : return;
930 : __get_seccomp_filter(orig);
931 : refcount_inc(&orig->users);
932 : }
933 :
934 : #endif /* CONFIG_SECCOMP_FILTER */
935 :
936 : /* For use with seccomp_actions_logged */
937 : #define SECCOMP_LOG_KILL_PROCESS (1 << 0)
938 : #define SECCOMP_LOG_KILL_THREAD (1 << 1)
939 : #define SECCOMP_LOG_TRAP (1 << 2)
940 : #define SECCOMP_LOG_ERRNO (1 << 3)
941 : #define SECCOMP_LOG_TRACE (1 << 4)
942 : #define SECCOMP_LOG_LOG (1 << 5)
943 : #define SECCOMP_LOG_ALLOW (1 << 6)
944 : #define SECCOMP_LOG_USER_NOTIF (1 << 7)
945 :
946 : static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS |
947 : SECCOMP_LOG_KILL_THREAD |
948 : SECCOMP_LOG_TRAP |
949 : SECCOMP_LOG_ERRNO |
950 : SECCOMP_LOG_USER_NOTIF |
951 : SECCOMP_LOG_TRACE |
952 : SECCOMP_LOG_LOG;
953 :
954 : static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
955 : bool requested)
956 : {
957 0 : bool log = false;
958 :
959 : switch (action) {
960 : case SECCOMP_RET_ALLOW:
961 : break;
962 : case SECCOMP_RET_TRAP:
963 : log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP;
964 : break;
965 : case SECCOMP_RET_ERRNO:
966 : log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO;
967 : break;
968 : case SECCOMP_RET_TRACE:
969 : log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE;
970 : break;
971 : case SECCOMP_RET_USER_NOTIF:
972 : log = requested && seccomp_actions_logged & SECCOMP_LOG_USER_NOTIF;
973 : break;
974 : case SECCOMP_RET_LOG:
975 : log = seccomp_actions_logged & SECCOMP_LOG_LOG;
976 : break;
977 : case SECCOMP_RET_KILL_THREAD:
978 : log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD;
979 : break;
980 : case SECCOMP_RET_KILL_PROCESS:
981 : default:
982 : log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS;
983 : }
984 :
985 : /*
986 : * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
987 : * FILTER_FLAG_LOG bit was set. The admin has the ability to silence
988 : * any action from being logged by removing the action name from the
989 : * seccomp_actions_logged sysctl.
990 : */
991 : if (!log)
992 : return;
993 :
994 : audit_seccomp(syscall, signr, action);
995 : }
996 :
997 : /*
998 : * Secure computing mode 1 allows only read/write/exit/sigreturn.
999 : * To be fully secure this must be combined with rlimit
1000 : * to limit the stack allocations too.
1001 : */
1002 : static const int mode1_syscalls[] = {
1003 : __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
1004 : -1, /* negative terminated */
1005 : };
1006 :
1007 0 : static void __secure_computing_strict(int this_syscall)
1008 : {
1009 0 : const int *allowed_syscalls = mode1_syscalls;
1010 : #ifdef CONFIG_COMPAT
1011 : if (in_compat_syscall())
1012 : allowed_syscalls = get_compat_mode1_syscalls();
1013 : #endif
1014 : do {
1015 0 : if (*allowed_syscalls == this_syscall)
1016 0 : return;
1017 0 : } while (*++allowed_syscalls != -1);
1018 :
1019 : #ifdef SECCOMP_DEBUG
1020 : dump_stack();
1021 : #endif
1022 0 : current->seccomp.mode = SECCOMP_MODE_DEAD;
1023 0 : seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
1024 0 : do_exit(SIGKILL);
1025 : }
1026 :
1027 : #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
1028 : void secure_computing_strict(int this_syscall)
1029 : {
1030 : int mode = current->seccomp.mode;
1031 :
1032 : if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
1033 : unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
1034 : return;
1035 :
1036 : if (mode == SECCOMP_MODE_DISABLED)
1037 : return;
1038 : else if (mode == SECCOMP_MODE_STRICT)
1039 : __secure_computing_strict(this_syscall);
1040 : else
1041 : BUG();
1042 : }
1043 : #else
1044 :
1045 : #ifdef CONFIG_SECCOMP_FILTER
1046 : static u64 seccomp_next_notify_id(struct seccomp_filter *filter)
1047 : {
1048 : /*
1049 : * Note: overflow is ok here, the id just needs to be unique per
1050 : * filter.
1051 : */
1052 : lockdep_assert_held(&filter->notify_lock);
1053 : return filter->notif->next_id++;
1054 : }
1055 :
1056 : static void seccomp_handle_addfd(struct seccomp_kaddfd *addfd, struct seccomp_knotif *n)
1057 : {
1058 : int fd;
1059 :
1060 : /*
1061 : * Remove the notification, and reset the list pointers, indicating
1062 : * that it has been handled.
1063 : */
1064 : list_del_init(&addfd->list);
1065 : if (!addfd->setfd)
1066 : fd = receive_fd(addfd->file, addfd->flags);
1067 : else
1068 : fd = receive_fd_replace(addfd->fd, addfd->file, addfd->flags);
1069 : addfd->ret = fd;
1070 :
1071 : if (addfd->ioctl_flags & SECCOMP_ADDFD_FLAG_SEND) {
1072 : /* If we fail reset and return an error to the notifier */
1073 : if (fd < 0) {
1074 : n->state = SECCOMP_NOTIFY_SENT;
1075 : } else {
1076 : /* Return the FD we just added */
1077 : n->flags = 0;
1078 : n->error = 0;
1079 : n->val = fd;
1080 : }
1081 : }
1082 :
1083 : /*
1084 : * Mark the notification as completed. From this point, addfd mem
1085 : * might be invalidated and we can't safely read it anymore.
1086 : */
1087 : complete(&addfd->completion);
1088 : }
1089 :
1090 : static bool should_sleep_killable(struct seccomp_filter *match,
1091 : struct seccomp_knotif *n)
1092 : {
1093 : return match->wait_killable_recv && n->state == SECCOMP_NOTIFY_SENT;
1094 : }
1095 :
1096 : static int seccomp_do_user_notification(int this_syscall,
1097 : struct seccomp_filter *match,
1098 : const struct seccomp_data *sd)
1099 : {
1100 : int err;
1101 : u32 flags = 0;
1102 : long ret = 0;
1103 : struct seccomp_knotif n = {};
1104 : struct seccomp_kaddfd *addfd, *tmp;
1105 :
1106 : mutex_lock(&match->notify_lock);
1107 : err = -ENOSYS;
1108 : if (!match->notif)
1109 : goto out;
1110 :
1111 : n.task = current;
1112 : n.state = SECCOMP_NOTIFY_INIT;
1113 : n.data = sd;
1114 : n.id = seccomp_next_notify_id(match);
1115 : init_completion(&n.ready);
1116 : list_add_tail(&n.list, &match->notif->notifications);
1117 : INIT_LIST_HEAD(&n.addfd);
1118 :
1119 : up(&match->notif->request);
1120 : wake_up_poll(&match->wqh, EPOLLIN | EPOLLRDNORM);
1121 :
1122 : /*
1123 : * This is where we wait for a reply from userspace.
1124 : */
1125 : do {
1126 : bool wait_killable = should_sleep_killable(match, &n);
1127 :
1128 : mutex_unlock(&match->notify_lock);
1129 : if (wait_killable)
1130 : err = wait_for_completion_killable(&n.ready);
1131 : else
1132 : err = wait_for_completion_interruptible(&n.ready);
1133 : mutex_lock(&match->notify_lock);
1134 :
1135 : if (err != 0) {
1136 : /*
1137 : * Check to see if the notifcation got picked up and
1138 : * whether we should switch to wait killable.
1139 : */
1140 : if (!wait_killable && should_sleep_killable(match, &n))
1141 : continue;
1142 :
1143 : goto interrupted;
1144 : }
1145 :
1146 : addfd = list_first_entry_or_null(&n.addfd,
1147 : struct seccomp_kaddfd, list);
1148 : /* Check if we were woken up by a addfd message */
1149 : if (addfd)
1150 : seccomp_handle_addfd(addfd, &n);
1151 :
1152 : } while (n.state != SECCOMP_NOTIFY_REPLIED);
1153 :
1154 : ret = n.val;
1155 : err = n.error;
1156 : flags = n.flags;
1157 :
1158 : interrupted:
1159 : /* If there were any pending addfd calls, clear them out */
1160 : list_for_each_entry_safe(addfd, tmp, &n.addfd, list) {
1161 : /* The process went away before we got a chance to handle it */
1162 : addfd->ret = -ESRCH;
1163 : list_del_init(&addfd->list);
1164 : complete(&addfd->completion);
1165 : }
1166 :
1167 : /*
1168 : * Note that it's possible the listener died in between the time when
1169 : * we were notified of a response (or a signal) and when we were able to
1170 : * re-acquire the lock, so only delete from the list if the
1171 : * notification actually exists.
1172 : *
1173 : * Also note that this test is only valid because there's no way to
1174 : * *reattach* to a notifier right now. If one is added, we'll need to
1175 : * keep track of the notif itself and make sure they match here.
1176 : */
1177 : if (match->notif)
1178 : list_del(&n.list);
1179 : out:
1180 : mutex_unlock(&match->notify_lock);
1181 :
1182 : /* Userspace requests to continue the syscall. */
1183 : if (flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE)
1184 : return 0;
1185 :
1186 : syscall_set_return_value(current, current_pt_regs(),
1187 : err, ret);
1188 : return -1;
1189 : }
1190 :
1191 : static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
1192 : const bool recheck_after_trace)
1193 : {
1194 : u32 filter_ret, action;
1195 : struct seccomp_filter *match = NULL;
1196 : int data;
1197 : struct seccomp_data sd_local;
1198 :
1199 : /*
1200 : * Make sure that any changes to mode from another thread have
1201 : * been seen after SYSCALL_WORK_SECCOMP was seen.
1202 : */
1203 : smp_rmb();
1204 :
1205 : if (!sd) {
1206 : populate_seccomp_data(&sd_local);
1207 : sd = &sd_local;
1208 : }
1209 :
1210 : filter_ret = seccomp_run_filters(sd, &match);
1211 : data = filter_ret & SECCOMP_RET_DATA;
1212 : action = filter_ret & SECCOMP_RET_ACTION_FULL;
1213 :
1214 : switch (action) {
1215 : case SECCOMP_RET_ERRNO:
1216 : /* Set low-order bits as an errno, capped at MAX_ERRNO. */
1217 : if (data > MAX_ERRNO)
1218 : data = MAX_ERRNO;
1219 : syscall_set_return_value(current, current_pt_regs(),
1220 : -data, 0);
1221 : goto skip;
1222 :
1223 : case SECCOMP_RET_TRAP:
1224 : /* Show the handler the original registers. */
1225 : syscall_rollback(current, current_pt_regs());
1226 : /* Let the filter pass back 16 bits of data. */
1227 : force_sig_seccomp(this_syscall, data, false);
1228 : goto skip;
1229 :
1230 : case SECCOMP_RET_TRACE:
1231 : /* We've been put in this state by the ptracer already. */
1232 : if (recheck_after_trace)
1233 : return 0;
1234 :
1235 : /* ENOSYS these calls if there is no tracer attached. */
1236 : if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
1237 : syscall_set_return_value(current,
1238 : current_pt_regs(),
1239 : -ENOSYS, 0);
1240 : goto skip;
1241 : }
1242 :
1243 : /* Allow the BPF to provide the event message */
1244 : ptrace_event(PTRACE_EVENT_SECCOMP, data);
1245 : /*
1246 : * The delivery of a fatal signal during event
1247 : * notification may silently skip tracer notification,
1248 : * which could leave us with a potentially unmodified
1249 : * syscall that the tracer would have liked to have
1250 : * changed. Since the process is about to die, we just
1251 : * force the syscall to be skipped and let the signal
1252 : * kill the process and correctly handle any tracer exit
1253 : * notifications.
1254 : */
1255 : if (fatal_signal_pending(current))
1256 : goto skip;
1257 : /* Check if the tracer forced the syscall to be skipped. */
1258 : this_syscall = syscall_get_nr(current, current_pt_regs());
1259 : if (this_syscall < 0)
1260 : goto skip;
1261 :
1262 : /*
1263 : * Recheck the syscall, since it may have changed. This
1264 : * intentionally uses a NULL struct seccomp_data to force
1265 : * a reload of all registers. This does not goto skip since
1266 : * a skip would have already been reported.
1267 : */
1268 : if (__seccomp_filter(this_syscall, NULL, true))
1269 : return -1;
1270 :
1271 : return 0;
1272 :
1273 : case SECCOMP_RET_USER_NOTIF:
1274 : if (seccomp_do_user_notification(this_syscall, match, sd))
1275 : goto skip;
1276 :
1277 : return 0;
1278 :
1279 : case SECCOMP_RET_LOG:
1280 : seccomp_log(this_syscall, 0, action, true);
1281 : return 0;
1282 :
1283 : case SECCOMP_RET_ALLOW:
1284 : /*
1285 : * Note that the "match" filter will always be NULL for
1286 : * this action since SECCOMP_RET_ALLOW is the starting
1287 : * state in seccomp_run_filters().
1288 : */
1289 : return 0;
1290 :
1291 : case SECCOMP_RET_KILL_THREAD:
1292 : case SECCOMP_RET_KILL_PROCESS:
1293 : default:
1294 : current->seccomp.mode = SECCOMP_MODE_DEAD;
1295 : seccomp_log(this_syscall, SIGSYS, action, true);
1296 : /* Dump core only if this is the last remaining thread. */
1297 : if (action != SECCOMP_RET_KILL_THREAD ||
1298 : (atomic_read(¤t->signal->live) == 1)) {
1299 : /* Show the original registers in the dump. */
1300 : syscall_rollback(current, current_pt_regs());
1301 : /* Trigger a coredump with SIGSYS */
1302 : force_sig_seccomp(this_syscall, data, true);
1303 : } else {
1304 : do_exit(SIGSYS);
1305 : }
1306 : return -1; /* skip the syscall go directly to signal handling */
1307 : }
1308 :
1309 : unreachable();
1310 :
1311 : skip:
1312 : seccomp_log(this_syscall, 0, action, match ? match->log : false);
1313 : return -1;
1314 : }
1315 : #else
1316 0 : static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
1317 : const bool recheck_after_trace)
1318 : {
1319 0 : BUG();
1320 :
1321 : return -1;
1322 : }
1323 : #endif
1324 :
1325 0 : int __secure_computing(const struct seccomp_data *sd)
1326 : {
1327 0 : int mode = current->seccomp.mode;
1328 : int this_syscall;
1329 :
1330 : if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
1331 : unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
1332 : return 0;
1333 :
1334 0 : this_syscall = sd ? sd->nr :
1335 0 : syscall_get_nr(current, current_pt_regs());
1336 :
1337 0 : switch (mode) {
1338 : case SECCOMP_MODE_STRICT:
1339 0 : __secure_computing_strict(this_syscall); /* may call do_exit */
1340 : return 0;
1341 : case SECCOMP_MODE_FILTER:
1342 0 : return __seccomp_filter(this_syscall, sd, false);
1343 : /* Surviving SECCOMP_RET_KILL_* must be proactively impossible. */
1344 : case SECCOMP_MODE_DEAD:
1345 0 : WARN_ON_ONCE(1);
1346 0 : do_exit(SIGKILL);
1347 : return -1;
1348 : default:
1349 0 : BUG();
1350 : }
1351 : }
1352 : #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
1353 :
1354 0 : long prctl_get_seccomp(void)
1355 : {
1356 0 : return current->seccomp.mode;
1357 : }
1358 :
1359 : /**
1360 : * seccomp_set_mode_strict: internal function for setting strict seccomp
1361 : *
1362 : * Once current->seccomp.mode is non-zero, it may not be changed.
1363 : *
1364 : * Returns 0 on success or -EINVAL on failure.
1365 : */
1366 0 : static long seccomp_set_mode_strict(void)
1367 : {
1368 0 : const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
1369 0 : long ret = -EINVAL;
1370 :
1371 0 : spin_lock_irq(¤t->sighand->siglock);
1372 :
1373 0 : if (!seccomp_may_assign_mode(seccomp_mode))
1374 : goto out;
1375 :
1376 : #ifdef TIF_NOTSC
1377 : disable_TSC();
1378 : #endif
1379 0 : seccomp_assign_mode(current, seccomp_mode, 0);
1380 0 : ret = 0;
1381 :
1382 : out:
1383 0 : spin_unlock_irq(¤t->sighand->siglock);
1384 :
1385 0 : return ret;
1386 : }
1387 :
1388 : #ifdef CONFIG_SECCOMP_FILTER
1389 : static void seccomp_notify_free(struct seccomp_filter *filter)
1390 : {
1391 : kfree(filter->notif);
1392 : filter->notif = NULL;
1393 : }
1394 :
1395 : static void seccomp_notify_detach(struct seccomp_filter *filter)
1396 : {
1397 : struct seccomp_knotif *knotif;
1398 :
1399 : if (!filter)
1400 : return;
1401 :
1402 : mutex_lock(&filter->notify_lock);
1403 :
1404 : /*
1405 : * If this file is being closed because e.g. the task who owned it
1406 : * died, let's wake everyone up who was waiting on us.
1407 : */
1408 : list_for_each_entry(knotif, &filter->notif->notifications, list) {
1409 : if (knotif->state == SECCOMP_NOTIFY_REPLIED)
1410 : continue;
1411 :
1412 : knotif->state = SECCOMP_NOTIFY_REPLIED;
1413 : knotif->error = -ENOSYS;
1414 : knotif->val = 0;
1415 :
1416 : /*
1417 : * We do not need to wake up any pending addfd messages, as
1418 : * the notifier will do that for us, as this just looks
1419 : * like a standard reply.
1420 : */
1421 : complete(&knotif->ready);
1422 : }
1423 :
1424 : seccomp_notify_free(filter);
1425 : mutex_unlock(&filter->notify_lock);
1426 : }
1427 :
1428 : static int seccomp_notify_release(struct inode *inode, struct file *file)
1429 : {
1430 : struct seccomp_filter *filter = file->private_data;
1431 :
1432 : seccomp_notify_detach(filter);
1433 : __put_seccomp_filter(filter);
1434 : return 0;
1435 : }
1436 :
1437 : /* must be called with notif_lock held */
1438 : static inline struct seccomp_knotif *
1439 : find_notification(struct seccomp_filter *filter, u64 id)
1440 : {
1441 : struct seccomp_knotif *cur;
1442 :
1443 : lockdep_assert_held(&filter->notify_lock);
1444 :
1445 : list_for_each_entry(cur, &filter->notif->notifications, list) {
1446 : if (cur->id == id)
1447 : return cur;
1448 : }
1449 :
1450 : return NULL;
1451 : }
1452 :
1453 :
1454 : static long seccomp_notify_recv(struct seccomp_filter *filter,
1455 : void __user *buf)
1456 : {
1457 : struct seccomp_knotif *knotif = NULL, *cur;
1458 : struct seccomp_notif unotif;
1459 : ssize_t ret;
1460 :
1461 : /* Verify that we're not given garbage to keep struct extensible. */
1462 : ret = check_zeroed_user(buf, sizeof(unotif));
1463 : if (ret < 0)
1464 : return ret;
1465 : if (!ret)
1466 : return -EINVAL;
1467 :
1468 : memset(&unotif, 0, sizeof(unotif));
1469 :
1470 : ret = down_interruptible(&filter->notif->request);
1471 : if (ret < 0)
1472 : return ret;
1473 :
1474 : mutex_lock(&filter->notify_lock);
1475 : list_for_each_entry(cur, &filter->notif->notifications, list) {
1476 : if (cur->state == SECCOMP_NOTIFY_INIT) {
1477 : knotif = cur;
1478 : break;
1479 : }
1480 : }
1481 :
1482 : /*
1483 : * If we didn't find a notification, it could be that the task was
1484 : * interrupted by a fatal signal between the time we were woken and
1485 : * when we were able to acquire the rw lock.
1486 : */
1487 : if (!knotif) {
1488 : ret = -ENOENT;
1489 : goto out;
1490 : }
1491 :
1492 : unotif.id = knotif->id;
1493 : unotif.pid = task_pid_vnr(knotif->task);
1494 : unotif.data = *(knotif->data);
1495 :
1496 : knotif->state = SECCOMP_NOTIFY_SENT;
1497 : wake_up_poll(&filter->wqh, EPOLLOUT | EPOLLWRNORM);
1498 : ret = 0;
1499 : out:
1500 : mutex_unlock(&filter->notify_lock);
1501 :
1502 : if (ret == 0 && copy_to_user(buf, &unotif, sizeof(unotif))) {
1503 : ret = -EFAULT;
1504 :
1505 : /*
1506 : * Userspace screwed up. To make sure that we keep this
1507 : * notification alive, let's reset it back to INIT. It
1508 : * may have died when we released the lock, so we need to make
1509 : * sure it's still around.
1510 : */
1511 : mutex_lock(&filter->notify_lock);
1512 : knotif = find_notification(filter, unotif.id);
1513 : if (knotif) {
1514 : /* Reset the process to make sure it's not stuck */
1515 : if (should_sleep_killable(filter, knotif))
1516 : complete(&knotif->ready);
1517 : knotif->state = SECCOMP_NOTIFY_INIT;
1518 : up(&filter->notif->request);
1519 : }
1520 : mutex_unlock(&filter->notify_lock);
1521 : }
1522 :
1523 : return ret;
1524 : }
1525 :
1526 : static long seccomp_notify_send(struct seccomp_filter *filter,
1527 : void __user *buf)
1528 : {
1529 : struct seccomp_notif_resp resp = {};
1530 : struct seccomp_knotif *knotif;
1531 : long ret;
1532 :
1533 : if (copy_from_user(&resp, buf, sizeof(resp)))
1534 : return -EFAULT;
1535 :
1536 : if (resp.flags & ~SECCOMP_USER_NOTIF_FLAG_CONTINUE)
1537 : return -EINVAL;
1538 :
1539 : if ((resp.flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE) &&
1540 : (resp.error || resp.val))
1541 : return -EINVAL;
1542 :
1543 : ret = mutex_lock_interruptible(&filter->notify_lock);
1544 : if (ret < 0)
1545 : return ret;
1546 :
1547 : knotif = find_notification(filter, resp.id);
1548 : if (!knotif) {
1549 : ret = -ENOENT;
1550 : goto out;
1551 : }
1552 :
1553 : /* Allow exactly one reply. */
1554 : if (knotif->state != SECCOMP_NOTIFY_SENT) {
1555 : ret = -EINPROGRESS;
1556 : goto out;
1557 : }
1558 :
1559 : ret = 0;
1560 : knotif->state = SECCOMP_NOTIFY_REPLIED;
1561 : knotif->error = resp.error;
1562 : knotif->val = resp.val;
1563 : knotif->flags = resp.flags;
1564 : complete(&knotif->ready);
1565 : out:
1566 : mutex_unlock(&filter->notify_lock);
1567 : return ret;
1568 : }
1569 :
1570 : static long seccomp_notify_id_valid(struct seccomp_filter *filter,
1571 : void __user *buf)
1572 : {
1573 : struct seccomp_knotif *knotif;
1574 : u64 id;
1575 : long ret;
1576 :
1577 : if (copy_from_user(&id, buf, sizeof(id)))
1578 : return -EFAULT;
1579 :
1580 : ret = mutex_lock_interruptible(&filter->notify_lock);
1581 : if (ret < 0)
1582 : return ret;
1583 :
1584 : knotif = find_notification(filter, id);
1585 : if (knotif && knotif->state == SECCOMP_NOTIFY_SENT)
1586 : ret = 0;
1587 : else
1588 : ret = -ENOENT;
1589 :
1590 : mutex_unlock(&filter->notify_lock);
1591 : return ret;
1592 : }
1593 :
1594 : static long seccomp_notify_addfd(struct seccomp_filter *filter,
1595 : struct seccomp_notif_addfd __user *uaddfd,
1596 : unsigned int size)
1597 : {
1598 : struct seccomp_notif_addfd addfd;
1599 : struct seccomp_knotif *knotif;
1600 : struct seccomp_kaddfd kaddfd;
1601 : int ret;
1602 :
1603 : BUILD_BUG_ON(sizeof(addfd) < SECCOMP_NOTIFY_ADDFD_SIZE_VER0);
1604 : BUILD_BUG_ON(sizeof(addfd) != SECCOMP_NOTIFY_ADDFD_SIZE_LATEST);
1605 :
1606 : if (size < SECCOMP_NOTIFY_ADDFD_SIZE_VER0 || size >= PAGE_SIZE)
1607 : return -EINVAL;
1608 :
1609 : ret = copy_struct_from_user(&addfd, sizeof(addfd), uaddfd, size);
1610 : if (ret)
1611 : return ret;
1612 :
1613 : if (addfd.newfd_flags & ~O_CLOEXEC)
1614 : return -EINVAL;
1615 :
1616 : if (addfd.flags & ~(SECCOMP_ADDFD_FLAG_SETFD | SECCOMP_ADDFD_FLAG_SEND))
1617 : return -EINVAL;
1618 :
1619 : if (addfd.newfd && !(addfd.flags & SECCOMP_ADDFD_FLAG_SETFD))
1620 : return -EINVAL;
1621 :
1622 : kaddfd.file = fget(addfd.srcfd);
1623 : if (!kaddfd.file)
1624 : return -EBADF;
1625 :
1626 : kaddfd.ioctl_flags = addfd.flags;
1627 : kaddfd.flags = addfd.newfd_flags;
1628 : kaddfd.setfd = addfd.flags & SECCOMP_ADDFD_FLAG_SETFD;
1629 : kaddfd.fd = addfd.newfd;
1630 : init_completion(&kaddfd.completion);
1631 :
1632 : ret = mutex_lock_interruptible(&filter->notify_lock);
1633 : if (ret < 0)
1634 : goto out;
1635 :
1636 : knotif = find_notification(filter, addfd.id);
1637 : if (!knotif) {
1638 : ret = -ENOENT;
1639 : goto out_unlock;
1640 : }
1641 :
1642 : /*
1643 : * We do not want to allow for FD injection to occur before the
1644 : * notification has been picked up by a userspace handler, or after
1645 : * the notification has been replied to.
1646 : */
1647 : if (knotif->state != SECCOMP_NOTIFY_SENT) {
1648 : ret = -EINPROGRESS;
1649 : goto out_unlock;
1650 : }
1651 :
1652 : if (addfd.flags & SECCOMP_ADDFD_FLAG_SEND) {
1653 : /*
1654 : * Disallow queuing an atomic addfd + send reply while there are
1655 : * some addfd requests still to process.
1656 : *
1657 : * There is no clear reason to support it and allows us to keep
1658 : * the loop on the other side straight-forward.
1659 : */
1660 : if (!list_empty(&knotif->addfd)) {
1661 : ret = -EBUSY;
1662 : goto out_unlock;
1663 : }
1664 :
1665 : /* Allow exactly only one reply */
1666 : knotif->state = SECCOMP_NOTIFY_REPLIED;
1667 : }
1668 :
1669 : list_add(&kaddfd.list, &knotif->addfd);
1670 : complete(&knotif->ready);
1671 : mutex_unlock(&filter->notify_lock);
1672 :
1673 : /* Now we wait for it to be processed or be interrupted */
1674 : ret = wait_for_completion_interruptible(&kaddfd.completion);
1675 : if (ret == 0) {
1676 : /*
1677 : * We had a successful completion. The other side has already
1678 : * removed us from the addfd queue, and
1679 : * wait_for_completion_interruptible has a memory barrier upon
1680 : * success that lets us read this value directly without
1681 : * locking.
1682 : */
1683 : ret = kaddfd.ret;
1684 : goto out;
1685 : }
1686 :
1687 : mutex_lock(&filter->notify_lock);
1688 : /*
1689 : * Even though we were woken up by a signal and not a successful
1690 : * completion, a completion may have happened in the mean time.
1691 : *
1692 : * We need to check again if the addfd request has been handled,
1693 : * and if not, we will remove it from the queue.
1694 : */
1695 : if (list_empty(&kaddfd.list))
1696 : ret = kaddfd.ret;
1697 : else
1698 : list_del(&kaddfd.list);
1699 :
1700 : out_unlock:
1701 : mutex_unlock(&filter->notify_lock);
1702 : out:
1703 : fput(kaddfd.file);
1704 :
1705 : return ret;
1706 : }
1707 :
1708 : static long seccomp_notify_ioctl(struct file *file, unsigned int cmd,
1709 : unsigned long arg)
1710 : {
1711 : struct seccomp_filter *filter = file->private_data;
1712 : void __user *buf = (void __user *)arg;
1713 :
1714 : /* Fixed-size ioctls */
1715 : switch (cmd) {
1716 : case SECCOMP_IOCTL_NOTIF_RECV:
1717 : return seccomp_notify_recv(filter, buf);
1718 : case SECCOMP_IOCTL_NOTIF_SEND:
1719 : return seccomp_notify_send(filter, buf);
1720 : case SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR:
1721 : case SECCOMP_IOCTL_NOTIF_ID_VALID:
1722 : return seccomp_notify_id_valid(filter, buf);
1723 : }
1724 :
1725 : /* Extensible Argument ioctls */
1726 : #define EA_IOCTL(cmd) ((cmd) & ~(IOC_INOUT | IOCSIZE_MASK))
1727 : switch (EA_IOCTL(cmd)) {
1728 : case EA_IOCTL(SECCOMP_IOCTL_NOTIF_ADDFD):
1729 : return seccomp_notify_addfd(filter, buf, _IOC_SIZE(cmd));
1730 : default:
1731 : return -EINVAL;
1732 : }
1733 : }
1734 :
1735 : static __poll_t seccomp_notify_poll(struct file *file,
1736 : struct poll_table_struct *poll_tab)
1737 : {
1738 : struct seccomp_filter *filter = file->private_data;
1739 : __poll_t ret = 0;
1740 : struct seccomp_knotif *cur;
1741 :
1742 : poll_wait(file, &filter->wqh, poll_tab);
1743 :
1744 : if (mutex_lock_interruptible(&filter->notify_lock) < 0)
1745 : return EPOLLERR;
1746 :
1747 : list_for_each_entry(cur, &filter->notif->notifications, list) {
1748 : if (cur->state == SECCOMP_NOTIFY_INIT)
1749 : ret |= EPOLLIN | EPOLLRDNORM;
1750 : if (cur->state == SECCOMP_NOTIFY_SENT)
1751 : ret |= EPOLLOUT | EPOLLWRNORM;
1752 : if ((ret & EPOLLIN) && (ret & EPOLLOUT))
1753 : break;
1754 : }
1755 :
1756 : mutex_unlock(&filter->notify_lock);
1757 :
1758 : if (refcount_read(&filter->users) == 0)
1759 : ret |= EPOLLHUP;
1760 :
1761 : return ret;
1762 : }
1763 :
1764 : static const struct file_operations seccomp_notify_ops = {
1765 : .poll = seccomp_notify_poll,
1766 : .release = seccomp_notify_release,
1767 : .unlocked_ioctl = seccomp_notify_ioctl,
1768 : .compat_ioctl = seccomp_notify_ioctl,
1769 : };
1770 :
1771 : static struct file *init_listener(struct seccomp_filter *filter)
1772 : {
1773 : struct file *ret;
1774 :
1775 : ret = ERR_PTR(-ENOMEM);
1776 : filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);
1777 : if (!filter->notif)
1778 : goto out;
1779 :
1780 : sema_init(&filter->notif->request, 0);
1781 : filter->notif->next_id = get_random_u64();
1782 : INIT_LIST_HEAD(&filter->notif->notifications);
1783 :
1784 : ret = anon_inode_getfile("seccomp notify", &seccomp_notify_ops,
1785 : filter, O_RDWR);
1786 : if (IS_ERR(ret))
1787 : goto out_notif;
1788 :
1789 : /* The file has a reference to it now */
1790 : __get_seccomp_filter(filter);
1791 :
1792 : out_notif:
1793 : if (IS_ERR(ret))
1794 : seccomp_notify_free(filter);
1795 : out:
1796 : return ret;
1797 : }
1798 :
1799 : /*
1800 : * Does @new_child have a listener while an ancestor also has a listener?
1801 : * If so, we'll want to reject this filter.
1802 : * This only has to be tested for the current process, even in the TSYNC case,
1803 : * because TSYNC installs @child with the same parent on all threads.
1804 : * Note that @new_child is not hooked up to its parent at this point yet, so
1805 : * we use current->seccomp.filter.
1806 : */
1807 : static bool has_duplicate_listener(struct seccomp_filter *new_child)
1808 : {
1809 : struct seccomp_filter *cur;
1810 :
1811 : /* must be protected against concurrent TSYNC */
1812 : lockdep_assert_held(¤t->sighand->siglock);
1813 :
1814 : if (!new_child->notif)
1815 : return false;
1816 : for (cur = current->seccomp.filter; cur; cur = cur->prev) {
1817 : if (cur->notif)
1818 : return true;
1819 : }
1820 :
1821 : return false;
1822 : }
1823 :
1824 : /**
1825 : * seccomp_set_mode_filter: internal function for setting seccomp filter
1826 : * @flags: flags to change filter behavior
1827 : * @filter: struct sock_fprog containing filter
1828 : *
1829 : * This function may be called repeatedly to install additional filters.
1830 : * Every filter successfully installed will be evaluated (in reverse order)
1831 : * for each system call the task makes.
1832 : *
1833 : * Once current->seccomp.mode is non-zero, it may not be changed.
1834 : *
1835 : * Returns 0 on success or -EINVAL on failure.
1836 : */
1837 : static long seccomp_set_mode_filter(unsigned int flags,
1838 : const char __user *filter)
1839 : {
1840 : const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
1841 : struct seccomp_filter *prepared = NULL;
1842 : long ret = -EINVAL;
1843 : int listener = -1;
1844 : struct file *listener_f = NULL;
1845 :
1846 : /* Validate flags. */
1847 : if (flags & ~SECCOMP_FILTER_FLAG_MASK)
1848 : return -EINVAL;
1849 :
1850 : /*
1851 : * In the successful case, NEW_LISTENER returns the new listener fd.
1852 : * But in the failure case, TSYNC returns the thread that died. If you
1853 : * combine these two flags, there's no way to tell whether something
1854 : * succeeded or failed. So, let's disallow this combination if the user
1855 : * has not explicitly requested no errors from TSYNC.
1856 : */
1857 : if ((flags & SECCOMP_FILTER_FLAG_TSYNC) &&
1858 : (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) &&
1859 : ((flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH) == 0))
1860 : return -EINVAL;
1861 :
1862 : /*
1863 : * The SECCOMP_FILTER_FLAG_WAIT_KILLABLE_SENT flag doesn't make sense
1864 : * without the SECCOMP_FILTER_FLAG_NEW_LISTENER flag.
1865 : */
1866 : if ((flags & SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV) &&
1867 : ((flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) == 0))
1868 : return -EINVAL;
1869 :
1870 : /* Prepare the new filter before holding any locks. */
1871 : prepared = seccomp_prepare_user_filter(filter);
1872 : if (IS_ERR(prepared))
1873 : return PTR_ERR(prepared);
1874 :
1875 : if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1876 : listener = get_unused_fd_flags(O_CLOEXEC);
1877 : if (listener < 0) {
1878 : ret = listener;
1879 : goto out_free;
1880 : }
1881 :
1882 : listener_f = init_listener(prepared);
1883 : if (IS_ERR(listener_f)) {
1884 : put_unused_fd(listener);
1885 : ret = PTR_ERR(listener_f);
1886 : goto out_free;
1887 : }
1888 : }
1889 :
1890 : /*
1891 : * Make sure we cannot change seccomp or nnp state via TSYNC
1892 : * while another thread is in the middle of calling exec.
1893 : */
1894 : if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
1895 : mutex_lock_killable(¤t->signal->cred_guard_mutex))
1896 : goto out_put_fd;
1897 :
1898 : spin_lock_irq(¤t->sighand->siglock);
1899 :
1900 : if (!seccomp_may_assign_mode(seccomp_mode))
1901 : goto out;
1902 :
1903 : if (has_duplicate_listener(prepared)) {
1904 : ret = -EBUSY;
1905 : goto out;
1906 : }
1907 :
1908 : ret = seccomp_attach_filter(flags, prepared);
1909 : if (ret)
1910 : goto out;
1911 : /* Do not free the successfully attached filter. */
1912 : prepared = NULL;
1913 :
1914 : seccomp_assign_mode(current, seccomp_mode, flags);
1915 : out:
1916 : spin_unlock_irq(¤t->sighand->siglock);
1917 : if (flags & SECCOMP_FILTER_FLAG_TSYNC)
1918 : mutex_unlock(¤t->signal->cred_guard_mutex);
1919 : out_put_fd:
1920 : if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
1921 : if (ret) {
1922 : listener_f->private_data = NULL;
1923 : fput(listener_f);
1924 : put_unused_fd(listener);
1925 : seccomp_notify_detach(prepared);
1926 : } else {
1927 : fd_install(listener, listener_f);
1928 : ret = listener;
1929 : }
1930 : }
1931 : out_free:
1932 : seccomp_filter_free(prepared);
1933 : return ret;
1934 : }
1935 : #else
1936 : static inline long seccomp_set_mode_filter(unsigned int flags,
1937 : const char __user *filter)
1938 : {
1939 : return -EINVAL;
1940 : }
1941 : #endif
1942 :
1943 0 : static long seccomp_get_action_avail(const char __user *uaction)
1944 : {
1945 : u32 action;
1946 :
1947 0 : if (copy_from_user(&action, uaction, sizeof(action)))
1948 : return -EFAULT;
1949 :
1950 0 : switch (action) {
1951 : case SECCOMP_RET_KILL_PROCESS:
1952 : case SECCOMP_RET_KILL_THREAD:
1953 : case SECCOMP_RET_TRAP:
1954 : case SECCOMP_RET_ERRNO:
1955 : case SECCOMP_RET_USER_NOTIF:
1956 : case SECCOMP_RET_TRACE:
1957 : case SECCOMP_RET_LOG:
1958 : case SECCOMP_RET_ALLOW:
1959 : break;
1960 : default:
1961 : return -EOPNOTSUPP;
1962 : }
1963 :
1964 0 : return 0;
1965 : }
1966 :
1967 : static long seccomp_get_notif_sizes(void __user *usizes)
1968 : {
1969 0 : struct seccomp_notif_sizes sizes = {
1970 : .seccomp_notif = sizeof(struct seccomp_notif),
1971 : .seccomp_notif_resp = sizeof(struct seccomp_notif_resp),
1972 : .seccomp_data = sizeof(struct seccomp_data),
1973 : };
1974 :
1975 0 : if (copy_to_user(usizes, &sizes, sizeof(sizes)))
1976 : return -EFAULT;
1977 :
1978 : return 0;
1979 : }
1980 :
1981 : /* Common entry point for both prctl and syscall. */
1982 0 : static long do_seccomp(unsigned int op, unsigned int flags,
1983 : void __user *uargs)
1984 : {
1985 0 : switch (op) {
1986 : case SECCOMP_SET_MODE_STRICT:
1987 0 : if (flags != 0 || uargs != NULL)
1988 : return -EINVAL;
1989 0 : return seccomp_set_mode_strict();
1990 : case SECCOMP_SET_MODE_FILTER:
1991 : return seccomp_set_mode_filter(flags, uargs);
1992 : case SECCOMP_GET_ACTION_AVAIL:
1993 0 : if (flags != 0)
1994 : return -EINVAL;
1995 :
1996 0 : return seccomp_get_action_avail(uargs);
1997 : case SECCOMP_GET_NOTIF_SIZES:
1998 0 : if (flags != 0)
1999 : return -EINVAL;
2000 :
2001 0 : return seccomp_get_notif_sizes(uargs);
2002 : default:
2003 : return -EINVAL;
2004 : }
2005 : }
2006 :
2007 0 : SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
2008 : void __user *, uargs)
2009 : {
2010 0 : return do_seccomp(op, flags, uargs);
2011 : }
2012 :
2013 : /**
2014 : * prctl_set_seccomp: configures current->seccomp.mode
2015 : * @seccomp_mode: requested mode to use
2016 : * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
2017 : *
2018 : * Returns 0 on success or -EINVAL on failure.
2019 : */
2020 0 : long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)
2021 : {
2022 : unsigned int op;
2023 : void __user *uargs;
2024 :
2025 0 : switch (seccomp_mode) {
2026 : case SECCOMP_MODE_STRICT:
2027 : op = SECCOMP_SET_MODE_STRICT;
2028 : /*
2029 : * Setting strict mode through prctl always ignored filter,
2030 : * so make sure it is always NULL here to pass the internal
2031 : * check in do_seccomp().
2032 : */
2033 : uargs = NULL;
2034 : break;
2035 : case SECCOMP_MODE_FILTER:
2036 0 : op = SECCOMP_SET_MODE_FILTER;
2037 0 : uargs = filter;
2038 0 : break;
2039 : default:
2040 : return -EINVAL;
2041 : }
2042 :
2043 : /* prctl interface doesn't have flags, so they are always zero. */
2044 0 : return do_seccomp(op, 0, uargs);
2045 : }
2046 :
2047 : #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
2048 : static struct seccomp_filter *get_nth_filter(struct task_struct *task,
2049 : unsigned long filter_off)
2050 : {
2051 : struct seccomp_filter *orig, *filter;
2052 : unsigned long count;
2053 :
2054 : /*
2055 : * Note: this is only correct because the caller should be the (ptrace)
2056 : * tracer of the task, otherwise lock_task_sighand is needed.
2057 : */
2058 : spin_lock_irq(&task->sighand->siglock);
2059 :
2060 : if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
2061 : spin_unlock_irq(&task->sighand->siglock);
2062 : return ERR_PTR(-EINVAL);
2063 : }
2064 :
2065 : orig = task->seccomp.filter;
2066 : __get_seccomp_filter(orig);
2067 : spin_unlock_irq(&task->sighand->siglock);
2068 :
2069 : count = 0;
2070 : for (filter = orig; filter; filter = filter->prev)
2071 : count++;
2072 :
2073 : if (filter_off >= count) {
2074 : filter = ERR_PTR(-ENOENT);
2075 : goto out;
2076 : }
2077 :
2078 : count -= filter_off;
2079 : for (filter = orig; filter && count > 1; filter = filter->prev)
2080 : count--;
2081 :
2082 : if (WARN_ON(count != 1 || !filter)) {
2083 : filter = ERR_PTR(-ENOENT);
2084 : goto out;
2085 : }
2086 :
2087 : __get_seccomp_filter(filter);
2088 :
2089 : out:
2090 : __put_seccomp_filter(orig);
2091 : return filter;
2092 : }
2093 :
2094 : long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
2095 : void __user *data)
2096 : {
2097 : struct seccomp_filter *filter;
2098 : struct sock_fprog_kern *fprog;
2099 : long ret;
2100 :
2101 : if (!capable(CAP_SYS_ADMIN) ||
2102 : current->seccomp.mode != SECCOMP_MODE_DISABLED) {
2103 : return -EACCES;
2104 : }
2105 :
2106 : filter = get_nth_filter(task, filter_off);
2107 : if (IS_ERR(filter))
2108 : return PTR_ERR(filter);
2109 :
2110 : fprog = filter->prog->orig_prog;
2111 : if (!fprog) {
2112 : /* This must be a new non-cBPF filter, since we save
2113 : * every cBPF filter's orig_prog above when
2114 : * CONFIG_CHECKPOINT_RESTORE is enabled.
2115 : */
2116 : ret = -EMEDIUMTYPE;
2117 : goto out;
2118 : }
2119 :
2120 : ret = fprog->len;
2121 : if (!data)
2122 : goto out;
2123 :
2124 : if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
2125 : ret = -EFAULT;
2126 :
2127 : out:
2128 : __put_seccomp_filter(filter);
2129 : return ret;
2130 : }
2131 :
2132 : long seccomp_get_metadata(struct task_struct *task,
2133 : unsigned long size, void __user *data)
2134 : {
2135 : long ret;
2136 : struct seccomp_filter *filter;
2137 : struct seccomp_metadata kmd = {};
2138 :
2139 : if (!capable(CAP_SYS_ADMIN) ||
2140 : current->seccomp.mode != SECCOMP_MODE_DISABLED) {
2141 : return -EACCES;
2142 : }
2143 :
2144 : size = min_t(unsigned long, size, sizeof(kmd));
2145 :
2146 : if (size < sizeof(kmd.filter_off))
2147 : return -EINVAL;
2148 :
2149 : if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off)))
2150 : return -EFAULT;
2151 :
2152 : filter = get_nth_filter(task, kmd.filter_off);
2153 : if (IS_ERR(filter))
2154 : return PTR_ERR(filter);
2155 :
2156 : if (filter->log)
2157 : kmd.flags |= SECCOMP_FILTER_FLAG_LOG;
2158 :
2159 : ret = size;
2160 : if (copy_to_user(data, &kmd, size))
2161 : ret = -EFAULT;
2162 :
2163 : __put_seccomp_filter(filter);
2164 : return ret;
2165 : }
2166 : #endif
2167 :
2168 : #ifdef CONFIG_SYSCTL
2169 :
2170 : /* Human readable action names for friendly sysctl interaction */
2171 : #define SECCOMP_RET_KILL_PROCESS_NAME "kill_process"
2172 : #define SECCOMP_RET_KILL_THREAD_NAME "kill_thread"
2173 : #define SECCOMP_RET_TRAP_NAME "trap"
2174 : #define SECCOMP_RET_ERRNO_NAME "errno"
2175 : #define SECCOMP_RET_USER_NOTIF_NAME "user_notif"
2176 : #define SECCOMP_RET_TRACE_NAME "trace"
2177 : #define SECCOMP_RET_LOG_NAME "log"
2178 : #define SECCOMP_RET_ALLOW_NAME "allow"
2179 :
2180 : static const char seccomp_actions_avail[] =
2181 : SECCOMP_RET_KILL_PROCESS_NAME " "
2182 : SECCOMP_RET_KILL_THREAD_NAME " "
2183 : SECCOMP_RET_TRAP_NAME " "
2184 : SECCOMP_RET_ERRNO_NAME " "
2185 : SECCOMP_RET_USER_NOTIF_NAME " "
2186 : SECCOMP_RET_TRACE_NAME " "
2187 : SECCOMP_RET_LOG_NAME " "
2188 : SECCOMP_RET_ALLOW_NAME;
2189 :
2190 : struct seccomp_log_name {
2191 : u32 log;
2192 : const char *name;
2193 : };
2194 :
2195 : static const struct seccomp_log_name seccomp_log_names[] = {
2196 : { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME },
2197 : { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME },
2198 : { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME },
2199 : { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME },
2200 : { SECCOMP_LOG_USER_NOTIF, SECCOMP_RET_USER_NOTIF_NAME },
2201 : { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME },
2202 : { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME },
2203 : { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME },
2204 : { }
2205 : };
2206 :
2207 0 : static bool seccomp_names_from_actions_logged(char *names, size_t size,
2208 : u32 actions_logged,
2209 : const char *sep)
2210 : {
2211 : const struct seccomp_log_name *cur;
2212 0 : bool append_sep = false;
2213 :
2214 0 : for (cur = seccomp_log_names; cur->name && size; cur++) {
2215 : ssize_t ret;
2216 :
2217 0 : if (!(actions_logged & cur->log))
2218 0 : continue;
2219 :
2220 0 : if (append_sep) {
2221 0 : ret = strscpy(names, sep, size);
2222 0 : if (ret < 0)
2223 : return false;
2224 :
2225 0 : names += ret;
2226 0 : size -= ret;
2227 : } else
2228 : append_sep = true;
2229 :
2230 0 : ret = strscpy(names, cur->name, size);
2231 0 : if (ret < 0)
2232 : return false;
2233 :
2234 0 : names += ret;
2235 0 : size -= ret;
2236 : }
2237 :
2238 : return true;
2239 : }
2240 :
2241 0 : static bool seccomp_action_logged_from_name(u32 *action_logged,
2242 : const char *name)
2243 : {
2244 : const struct seccomp_log_name *cur;
2245 :
2246 0 : for (cur = seccomp_log_names; cur->name; cur++) {
2247 0 : if (!strcmp(cur->name, name)) {
2248 0 : *action_logged = cur->log;
2249 0 : return true;
2250 : }
2251 : }
2252 :
2253 : return false;
2254 : }
2255 :
2256 0 : static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names)
2257 : {
2258 : char *name;
2259 :
2260 0 : *actions_logged = 0;
2261 0 : while ((name = strsep(&names, " ")) && *name) {
2262 0 : u32 action_logged = 0;
2263 :
2264 0 : if (!seccomp_action_logged_from_name(&action_logged, name))
2265 0 : return false;
2266 :
2267 0 : *actions_logged |= action_logged;
2268 : }
2269 :
2270 : return true;
2271 : }
2272 :
2273 0 : static int read_actions_logged(struct ctl_table *ro_table, void *buffer,
2274 : size_t *lenp, loff_t *ppos)
2275 : {
2276 : char names[sizeof(seccomp_actions_avail)];
2277 : struct ctl_table table;
2278 :
2279 0 : memset(names, 0, sizeof(names));
2280 :
2281 0 : if (!seccomp_names_from_actions_logged(names, sizeof(names),
2282 : seccomp_actions_logged, " "))
2283 : return -EINVAL;
2284 :
2285 0 : table = *ro_table;
2286 0 : table.data = names;
2287 0 : table.maxlen = sizeof(names);
2288 0 : return proc_dostring(&table, 0, buffer, lenp, ppos);
2289 : }
2290 :
2291 0 : static int write_actions_logged(struct ctl_table *ro_table, void *buffer,
2292 : size_t *lenp, loff_t *ppos, u32 *actions_logged)
2293 : {
2294 : char names[sizeof(seccomp_actions_avail)];
2295 : struct ctl_table table;
2296 : int ret;
2297 :
2298 0 : if (!capable(CAP_SYS_ADMIN))
2299 : return -EPERM;
2300 :
2301 0 : memset(names, 0, sizeof(names));
2302 :
2303 0 : table = *ro_table;
2304 0 : table.data = names;
2305 0 : table.maxlen = sizeof(names);
2306 0 : ret = proc_dostring(&table, 1, buffer, lenp, ppos);
2307 0 : if (ret)
2308 : return ret;
2309 :
2310 0 : if (!seccomp_actions_logged_from_names(actions_logged, table.data))
2311 : return -EINVAL;
2312 :
2313 0 : if (*actions_logged & SECCOMP_LOG_ALLOW)
2314 : return -EINVAL;
2315 :
2316 0 : seccomp_actions_logged = *actions_logged;
2317 0 : return 0;
2318 : }
2319 :
2320 : static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged,
2321 : int ret)
2322 : {
2323 : char names[sizeof(seccomp_actions_avail)];
2324 : char old_names[sizeof(seccomp_actions_avail)];
2325 0 : const char *new = names;
2326 0 : const char *old = old_names;
2327 :
2328 : if (!audit_enabled)
2329 : return;
2330 :
2331 : memset(names, 0, sizeof(names));
2332 : memset(old_names, 0, sizeof(old_names));
2333 :
2334 : if (ret)
2335 : new = "?";
2336 : else if (!actions_logged)
2337 : new = "(none)";
2338 : else if (!seccomp_names_from_actions_logged(names, sizeof(names),
2339 : actions_logged, ","))
2340 : new = "?";
2341 :
2342 : if (!old_actions_logged)
2343 : old = "(none)";
2344 : else if (!seccomp_names_from_actions_logged(old_names,
2345 : sizeof(old_names),
2346 : old_actions_logged, ","))
2347 : old = "?";
2348 :
2349 : return audit_seccomp_actions_logged(new, old, !ret);
2350 : }
2351 :
2352 0 : static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write,
2353 : void *buffer, size_t *lenp,
2354 : loff_t *ppos)
2355 : {
2356 : int ret;
2357 :
2358 0 : if (write) {
2359 0 : u32 actions_logged = 0;
2360 0 : u32 old_actions_logged = seccomp_actions_logged;
2361 :
2362 0 : ret = write_actions_logged(ro_table, buffer, lenp, ppos,
2363 : &actions_logged);
2364 0 : audit_actions_logged(actions_logged, old_actions_logged, ret);
2365 : } else
2366 0 : ret = read_actions_logged(ro_table, buffer, lenp, ppos);
2367 :
2368 0 : return ret;
2369 : }
2370 :
2371 : static struct ctl_table seccomp_sysctl_table[] = {
2372 : {
2373 : .procname = "actions_avail",
2374 : .data = (void *) &seccomp_actions_avail,
2375 : .maxlen = sizeof(seccomp_actions_avail),
2376 : .mode = 0444,
2377 : .proc_handler = proc_dostring,
2378 : },
2379 : {
2380 : .procname = "actions_logged",
2381 : .mode = 0644,
2382 : .proc_handler = seccomp_actions_logged_handler,
2383 : },
2384 : { }
2385 : };
2386 :
2387 1 : static int __init seccomp_sysctl_init(void)
2388 : {
2389 1 : register_sysctl_init("kernel/seccomp", seccomp_sysctl_table);
2390 1 : return 0;
2391 : }
2392 :
2393 : device_initcall(seccomp_sysctl_init)
2394 :
2395 : #endif /* CONFIG_SYSCTL */
2396 :
2397 : #ifdef CONFIG_SECCOMP_CACHE_DEBUG
2398 : /* Currently CONFIG_SECCOMP_CACHE_DEBUG implies SECCOMP_ARCH_NATIVE */
2399 : static void proc_pid_seccomp_cache_arch(struct seq_file *m, const char *name,
2400 : const void *bitmap, size_t bitmap_size)
2401 : {
2402 : int nr;
2403 :
2404 : for (nr = 0; nr < bitmap_size; nr++) {
2405 : bool cached = test_bit(nr, bitmap);
2406 : char *status = cached ? "ALLOW" : "FILTER";
2407 :
2408 : seq_printf(m, "%s %d %s\n", name, nr, status);
2409 : }
2410 : }
2411 :
2412 : int proc_pid_seccomp_cache(struct seq_file *m, struct pid_namespace *ns,
2413 : struct pid *pid, struct task_struct *task)
2414 : {
2415 : struct seccomp_filter *f;
2416 : unsigned long flags;
2417 :
2418 : /*
2419 : * We don't want some sandboxed process to know what their seccomp
2420 : * filters consist of.
2421 : */
2422 : if (!file_ns_capable(m->file, &init_user_ns, CAP_SYS_ADMIN))
2423 : return -EACCES;
2424 :
2425 : if (!lock_task_sighand(task, &flags))
2426 : return -ESRCH;
2427 :
2428 : f = READ_ONCE(task->seccomp.filter);
2429 : if (!f) {
2430 : unlock_task_sighand(task, &flags);
2431 : return 0;
2432 : }
2433 :
2434 : /* prevent filter from being freed while we are printing it */
2435 : __get_seccomp_filter(f);
2436 : unlock_task_sighand(task, &flags);
2437 :
2438 : proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_NATIVE_NAME,
2439 : f->cache.allow_native,
2440 : SECCOMP_ARCH_NATIVE_NR);
2441 :
2442 : #ifdef SECCOMP_ARCH_COMPAT
2443 : proc_pid_seccomp_cache_arch(m, SECCOMP_ARCH_COMPAT_NAME,
2444 : f->cache.allow_compat,
2445 : SECCOMP_ARCH_COMPAT_NR);
2446 : #endif /* SECCOMP_ARCH_COMPAT */
2447 :
2448 : __put_seccomp_filter(f);
2449 : return 0;
2450 : }
2451 : #endif /* CONFIG_SECCOMP_CACHE_DEBUG */
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